Now, many methods of converting values of time and frequency into electric signals and measuring them are used for the measurement of the time and frequency. In such electric measurement, the times to be measured is calculated, using clock signals which are references of the measurement, by detecting the number of the clock signals for one cycle. However, although wavelengths of the clock signals may be shortened in order to make the measurement times highly precise, there is a realistic limit also in the wavelengths of the generable clock signals. For this reason, it is very effective to make them highly precise how the fractional parts which are less than one cycle of the clock signals are measured. Therefore, for example in Nonpatent Document 1, the fractional parts are measured by converting them into voltage values using a capacitor.